Owls of North and Central California Part I

Northern California is hometo many of the owls found in North America: Great Gray, California Spotted, Barred, Great Horned, Western Screech, Flammulated, Northern Saw-whet, Northern Pygmy, Long-eared, Short-eared, Burrowing, Barn Owl. These species cover all territories, from plains to high mountains, forests to fields, farms to back yards.

Owls are considered raptors because they have killing talons and ripping beaks. One or another of them hunts everything from the smallest cricket to the fattest skunk. There are many differences, DNA not the least, that separate owls from the various diurnal raptors: owls do not have crops; because most of them hunt in dim light, they have poor color vision and unlike hawks and falcons, only a single focal point (area of enriched receptors) on the retina. None flies fast; all except the Burrowing Owl and Northern Pygmy fly silently. Most hunt as much by sound as by sight, and have developed special ears. Unlike humans, owls’ special hair cells in the cochlea will regenerate. Owls, unlike hawks but like falcons, do not build nests. They take over the nests of other animals or live in cavities.

Great Horned Owl (Bubo virginianus) Rightly called the Tiger of the Forest, this large hunter preys on a wide variety of mammals, birds, and reptiles. It is particularly fond of jackrabbits and skunks, and is not averse to taking the occasional house-cat left out at night. This impressive owl has protective coloring that makes it look like tree bark, allowing it to sleep safely in the daytime, and great golden eyes and peaked “horns.” These “horns” or “ear tufts” have nothing to do with hearing, but probably do have something to do with communication. The GHO lays eggs in January in stolen or abandoned hawk nests or caves or large cavities. The young hatch in February and March and remain dependent on their parents far longer than is true of most birds – sometimes until early autumn. This is the owl we hear in towns, suburbs, and forests calling out a deep “Hooo-hoo-hoo.” Though, like most raptors, the female GHO is larger than the male, she has a higher-pitched call.

Northern Spotted Owl – captive bird

California Spotted Owl (Strix occidentalis occidentalis) Cousin to the Northern Spotted, famous poster child for old-growth forests, this subspecies nests in the Sierra and Coastal ranges, hunting flying squirrels and wood rats. Its spotted feathering makes it blend in with sunlight dappling a tree trunk, and its dark eyes and round face give it a gentle expression. It is, in fact, rather too tame for its own good, sometimes allowing people to walk up to it. The preservation of old forests is important for all subspecies of this bird, which has adapted to that dark, close environment and to the small mammals that live there. The Spotted’s larger cousin, the Barred Owl (Strix varia Barton), which looks very like it, is much more adaptable – can eat anything (including a Spotted!) and live in many habitats, even near people. This owl is moving into California, down the Coastal Range, competing and sometimes interbreeding with the more vulnerable Spotted Owl. In a changing world, adaptability can mean survival.

Western Screech Owl

Western Screech Owl (Megascops [once Otus] kennicottii) Seen up close, these owls resemble miniature Great Horned Owls, with cryptic coloring and ear tufts. They are a successful species, adapting to life near humans, even moving into towns and cities, wherever there are large trees with nice cozy holes. Hunting at dawn and dusk, these birds capture small rodents, reptiles, and insects, especially large moths, which they snatch from the air. Before devouring their moths, Screeches remove the wings – if you find a pile of wings under a tree, you’ll know who is coming there to eat. You may also find pellets – indigestible leavings from the owls’ meals, which are compacted in the gizzard and then regurgitated, usually once a day. Screech Owl pellets are about the size of a quarter. Larger owls produce much larger pellets, even containing whole skeletons of their prey, since owls do not have the hawk’s strongly acidic digestive juices capable of “melting” large bony bits. Unfortunately for the Screech, the larger owls often target their small cousins, so it is not unheard of to find small owl bones in the pellets of the larger ones.

No wonder, then, that Screech Owls, though they are colored exactly like oak bark, and so are well camouflaged, prefer the safety of their little hidey-holes during the day. They use cavities created by fallen limbs, abandoned woodpecker holes, or even man-made boxes when the opening is the right size. They will lay eggs and raise chicks in the same safe crevice in the early spring and summer months.

Incidentally, these birds don’t live up to their common name: instead of a screech, they make a warbling noise, often descending in pitch, or a series of shorter warbling hoots. Among these owls, as with most raptors, the ladies are larger than the gentlemen, but the male owl’s voice is lower and louder. Their new scientific name, recently changed from “Otus” to “Megascops,” is more apt. “Scop” is Old English for a bard or musician, and is the genus name of many small owls in Europe. “Mega” means big, so the Western Screech Owl is the big little musical owl, named for the naturalist, Robert Kennicott.

(Part II will present more owl species)

Find the Owl! All owls, large and small, camouflage themselves to avoid predators. This GHO is nearly invisible in the abandoned Red-tail nest she has taken over.

I would love some advice about building some homes for these remarkable musicians. I live next to the Forest of Nicense Marks in Northern California. I understand that type of owl home built is dependent on species.

Vennessa – You are correct. While most owls are cavity nesters, the size of the cavity acceptable to a pair of owls depends on the size of the bird. I will do some research and get back to you, since the measurements are important.

My son is very concerned about several miles of roadway that he travels daily from Iselton into Sacramento and back. because he saw 2 owls and 2 hawks dead on the side of the Rd in 2 days last week. He went back yesterday and took pictures and counted 17 owls and 5 hawks ( 2 kinds of hawks ) . That’s 22 freshly killed birds plus other carcass es on various stated of decay. that were older He’s been trying to research see if something can be done to change this enviornment… like planting trees in the median, owl boxes etc. What can be done to help prevent theses collisions with cars? Most birds were on the inside lane /the fast lane of the roadway where the median is extremely wide with low growing grass like the farm areas on either side of the highway.

Dear Lisa – I work at the California Raptor Center in Davis, and we see many car-hit hawks, I’m afraid. This time of year there’ll be many young birds road-killed. It might help to know that most of us believe an increase in road-killed birds may indicate a large population of young birds for the year. But it doesn’t make it any easier to see them dead on the highway. Many young birds seem to seek the median areas of the roads because ground predators will be fewer there and yet there’ll still be voles and rabbits. The Environmental Impact folks for those Delta roads might be interested in a call from your son, particularly if he alerts to them a specific problem area. Call Cal-trans and see what they say about it. They may be working on mitigation already. Maybe having larger trees or bushes alongside the road for perching might help, as you say. But remember: young hungry birds zero in on prey, or on carrion, and they don’t seem to see the cars coming when they do that. Young birds are moving out of their nest areas now – their parents have stopped feeding them and they’ll go where easy prey is plentiful. Most are not really great at hunting yet, nor are they as cautious as they will be if they survive this first year. About 75 percent of any year’s new raptors won’t make it till Spring. Some of that is human-caused but not all of it. Though it seems really unfair: we offer something that looks good to them – a clear area with lots of rodents. And then come the cars. Anyhow, thanks to you and your son for caring. Many folks don’t.

Hi; I’d like to build a house for owls I live in Santa Rosa california. can you supply me with some dimensions and which direction for the entrance to face and how large should the entrance be, etc. any info that would help me get the house to get a tenant will be appreciated. Thanking you in advance for any info sent back to me. Leonard
707-525-8424

I live in Redding CA and on a ridge line where the north side of my home slopes down to a mixed oak greenbelt with a sparsely developed grass oak valley further below. Judging by the many pocket gophers, field mice, etc. that come into may yard from these areas below I was wondering it would be worth the effort to try placing an owl nesting box in the woodland below my backyard. If so, what owls might nest there and what would be box designs and dimensions.

I should note there is a female red shouldered hawk that lives in the valley below. She has been there for several years and roams the valley regularly each day. On and off she finds a mate and raises one to two youngsters.

Michael, you may try a Barn Owl box, if your valley is relatively open. They like the prey animals you mention and they can, if they have a large prey base, breed most of the year, raising up to 15 young barnies. You might also try a Screech Owl box. California Raptor Center has a design with instructions for hanging on its web site. if you make the Barn Owl box, you can make a Screech box only with a much smaller entry hole. I’ll have to ask around for an exact diameter, or you can look it up. CRC’s web page doesn’t give a design. it does have a Kestrel box design, which you can use, only make the hole much larger. I’m happy about your Red-shoulder! We have a pair near our house, as well. Have for years. Good luck!

Sorry to be so late getting back to you. The California Raptor Center’s webpage has instructions and a design for Barn Owl Boxes. That includes the size of the entrance, and I think they warn you not to have the box facing the hot summer sun (west) and it needs to have some shade. If you are trying to attract Screech Owls, the CRC’s design for the American Kestrel box would be the right size, but the opening would need to be about 4 inches, I think. Great Horned Owls don’t seem attracted to man-made boxes – they will steal a hawk or crow’s nest instead, or find a really big hole in a tree. Hope this helps.

we just had a owl move into our palm tree. have only seen it at night. wingspan I think is two and a half maybe three feet. Underside is white or gray. screeches. could you please help identify. p.s. great website.thank you so much .

Dear Steve, Thanks for the compliment. How did you find my website, if you don’t mind telling me? As to your owl, my best guess, since I haven’t seen or heard it, is a Barn Owl. Are you in a town or a farm? Barn Owls like palm trees, and often lay eggs in the old palm- frond tangles. The owlets sometimes drop out onto the ground. If this happens and the little fellow isn’t hurt, you might just gently tuck him into a basket and hang the basket up in the palm tree. The wingspan you mention is good for a Barn Owl, and the pale underside also. These birds scream and hiss. The Western Screech Owl is smaller and not so pale, and its vocalizations are varied, but really almost never a screech. You might google Barn Owls – there are some good photos on line. And Cornell’s Birds of North America online has good information. There is a free site from them. I don’t recall what it’s called, but if you google the bird, I’m sure it’ll come up.

thank you so much for your timely response. I believe I Found You by Googling owls indigenous to Sacramento. my wife and I both love your website and are very excited about our new addition. we live in North Highlands and the owl is in our palm tree. is it safe to assume that there will be a pair?

Alas, with wild critters, it is not safe to assume anything! But Barn Owls are prolific breeders and chances of a pair setting up housekeeping in your palm tree are good. In fact, they may already have eggs, though it is a bit early for that with Barnies. Still, if you have lots of prey animals about (mice are popular), they can raise up to 15 young per year. Keep me posted! Incidentally, they are fully capable of catching mice in total darkness, unlike most other owls common to our area. The Western Screech and the Great-horned Owl both seem to do better hunting at dawn and dusk. But – they didn’t read the books, so really almost anything is possible with these charming neighbors.

If you’re interested in seeing a Barn Owl up close, you can go, free, to the California Raptor Center in Davis. They have a collection of non-releasable hawks and owls, and among them, a female and a male Barn Owl. You can take the self-guided tour of the cages. The female’s name is Citrine; the male is Barney. They are not housed together, as Barney is rather fragile. He’s snowy white and a beauty. She’s dusky. If you go to the Raptor Center’s webpage, you’ll find directions for getting there. It’s easy. It’s a mile off the freeway, on Old Davis Road.

and again we thank you. that sounds like a lot of fun. we haven’t gotten a very good view of it yet. just the underside in the dark. however we continue to hear it up in the palm tree. thanks again, will keep you posted.

Not sure I have enough information to try to answer your question. Owls make an enormous variety of sounds, much more, I think, than most diurnal raptors, since they are communicating in the dark and so lack the daytime bird’s extraordinary visual capacities. Most owls click their beaks as a warning. Barn Owls do this less than the other families of owls. They tend to hiss or scream. Is this a Barn Owl you’re hearing?

Heard and spotted what looked and sounded like a Barred Owl in NE Fresno, near Cedar and Herndon Ave. An amazing sound totally unlike anything that I’ve ever heard in Fresno. It was about midnight and I was only about 50ft under the tree that he was calling from. Are Barred owl’s usually in this area?
Thanks for a very nice website!

Thanks, Ray. Barred Owls have been reported to be moving into the Central Valley. And since towns have rodents, I would not be surprised to find them there, but they are usually found in woods and forests. They look a good deal like a Spotted Owl. You might google Barred Owl to get pictures and go to Cornell’s site to get sounds. Owls in general have a very large repertory of calls, since they are abroad in dim light and can’t use the many visual signals other raptors do. The Barred Owls cries are particularly complex. I haven’t heard one in the flesh, so I’m envious! The other largish local owl whose calls are spine-chilling is the Long Eared. And it might move into town if there is a good prey base. It often hunts in the daytime and is familiar to birders in the Central Valley. I have not read much about the latest in the Barred Owl’s movements, but for some years, it has been recorded on the West Coast. It is known to be much more adaptable in habitat choice and food than its Spotted cousin. While you’re checking on the Barred, you might also see what you can find on Long-eared and Great Horned Owls. If it turns out you have a Barred, I’d like to know. We are all curious about this bird and its recent changes in life style.

We live in the foothills in Berry Creek, near Oroville. Heard a large number of strange sounds emanating from trees out in the front of our house, and no eye shine, so not a squirrel or raccoon. Finally saw these tiny grey owls, calling to each other, or they were annoyed at our flashlight. We saw one fly off its branch. It does have tiny “horns”. We think they might be babies, but saw and heard no larger and louder owls. Sounds kind of warbly. Do we have a bunch of Western Screech owls? Or some kind of pygmy owls? They are a lighter color on their underside, and light brownish.

Judy, you probably have Western Screeches. And possibly youngsters. They’d be flighted now – a year ago, I had three in my yard, playing musical fence posts. The tufts and warbly sounds say WESO to me. The lighter color on the undersides – and light brown – that could be other owls. Pygmys don’t really have tufts and they are out in the daylight often. Flammulated are smaller than Screech Owls, not as small as Pygmys. They have dark eyes. WESOs are common. And I usually pick the likeliest, if there’s a question. Google them and see if you can find photos that look like what you’ve seen. Good luck, and thanks for contacting me.